Specifications

HighWire MTP-2 - 1.2, September 4, 2002 Common Header Sub-Structures 51
initial_status
initial_statusinitial_status
initial_status
The initial value assigned to the transmission congestion state when the
current congestion level is 0 and the number of queued messages first
exceeds the congestion onset threshold. This value must be less than the
value of num_cong_levels
num_cong_levels num_cong_levels
num_cong_levels. Note that the timer Tx is not used in this instance.
rcv_pool_capacity
rcv_pool_capacity rcv_pool_capacity
rcv_pool_capacity
The capacity of the buffer pool used to receive messages from the partner
level 2.
Transmission congestion onset and abatement thresholds.
If cong_method
cong_method cong_method
cong_method is CBI_CONG_CTRL_NATL_WITH_PRI or
CBI_CONG_CTRL_NATL_BUFFER, the valid array indexes are 1 to
num_cong_levels
num_cong_levelsnum_cong_levels
num_cong_levels, representing the respective onset and abatement
thresholds.
• When the number of messages queued in L2’s transmit and retransmit
queues exceeds congestion onset threshold N, L2 sends an
M2_LINK_CONGESTED signal to L3 indicating a level of congestion equal
to N.
• When the number of queued messages falls below congestion abatement
threshold M, L2 sends an M2_LINK_CONGESTED signal to L3 indicating a
level of congestion equal to (M - 1).
• If a change in the number of messages queued causes the congestion
level to jump over more than one threshold, only one
M2_LINK_CONGESTED signal is sent. If the congestion is rising, the
congestion parameter of the M2_LINK_CONGESTED signal carries the
level of the largest onset threshold which is less than the current queue
size. If the congestion is falling, the congestion parameter carries the
level of the smallest abatement threshold that is greater than the current
queue size.
• The level N congestion abatement threshold must be greater than the
level (N-1) onset threshold.
If cong_method
cong_method cong_method
cong_method is CBI_CONG_CTRL_INTERNATIONAL, the valid array index is
0.
• When the number of messages queued in L2's transmit and retransmit
queues exceeds the congestion onset threshold, L2 sends an
M2_LINK_CONGESTED signal to L3 indicating a level of congestion of 1.
• When the queue length falls below the congestion abatement threshold,
L2 sends an M2_LINK_CONGSTN_CEASED signal to L3.
If cong_method
cong_method cong_method
cong_method is CBI_CONG_CTRL_NATL_TIMER, the valid array index is 0.
• See comments on t_tx_dur
t_tx_dur t_tx_dur
t_tx_dur and t_ty_dur
t_ty_dur t_ty_dur
t_ty_dur for how the onset and abatement
thresholds are used.
• When the congestion level changes, an M2_LINK_CONGESTED signal is
sent to L3.